Telegraph circuits



Aug. 4, 1925.

J. HERMAN TELEGRAPH CIRCUITS Filed April 5, 1922 l E-WNv-lllllllI-hl- INVENTOR. Y @ff/naw BYCQML l. LBMQL.

A TTORNF Patented Aug. 4, 1925.

UNITED sT Ares( YJOSEPH HERMAN, or NEW YORK, N. Y., AssIGNo'R rro AMERICAN TELEPHONE AND TELEGRAPH COMPANY, A coRPoRATIoN 0E NEWv YORK.

TELEGRAPH crRcrrs.

Appncarin rnieu Aprii 5, 1922. segial No. 549,689.

Toa-Ztwzom' t may concern:

Be it known that I, JOSEPH HERMAN, re-

siding at New York, in the county of'New' York and State of New York, have invented certain Improvements in Telegraph Cir-- cuits, of which the following is aspecication.

" This invention relates to telegraph systems and .more particularly to improvements 'in the apparatus and circuit arrangements of the telegraph sets utilized in such systems.

One of the features of the invention con- -sists in the use vof polar relays for the three functions of transmitting receiving and breaking whereby better'telegraph transmission andthe transmission of a v:a'pid break signal may be provided. A further feature of the invention consists in the elimination of the usual artiiicial line provided for duplex balance, and, accordingly, the maintenance of duplexV balance, which is one of the troublesome features of former arrangements, may be elminated. Further features and objects ofthe invention will appear more fully from the detailed description hereinafter given. A

The invention may be more fully uiideistood Y from the following description together with the accompanying drawing, in which is illustrateda-circuit diagram of the invention.

In the.y drawing isV shown a telegraph line LV interconnecting two stations A and B As the apparatus at each of the stations' A and B is substantially the same, similar reference 'characters with the added designation prime are utilized to denote like parte at both stations.. Aty station A is shown a pole changer relay 1 with the positive and negative batteries 2 and 3 respectively on its spacing and marking contacts designated as S and M` respectively. The pole changer y relay 1 has threev windings 4, 5 and 6. 4 and 5 are balanced windings, 11 being connected into a biasing circuit 8, and 5 nected into the loop circuit v7.y The third winding` 6 consists of a largenumber of turnsconnected across the armature and a contact of the receiving relay 10. It serves as a Aholding winding for the pole changer during the operation of the receiving relay 10. This arrangement has been disclosed in detail in a patent to JosephI-Ierman, No. 1,519,202, granted Dec. 16, 1924, and refer ence is had thereto. The loop circuit includes the batteries 11 and 12, the sounder S, the key K and the armature and contacts of the receiving relay 10. In theY loop circuit 'Tand the'biasing circuit 8 are also shown the windings of a balanced Vmeter 9. Associated with the marking contact and the armature of the receiving relay 10 in the loop circuit is the spark killer device, comprising the resistances 13 and 111 and the condenser 15 for purposes whichiwill be pointed out hereinafter. There isalso pro` vided a break relay 16. This relay has twol windings, 17 and 18. The winding17 con'- sistsof a small number of turns connected in series with the marking battery 3. The winding 18 consists of a large number ofv turns connected in a leak circuit 19 from the armature of the pole. changer relay 1 to ground. The armature of relay 16 is connected to the line L, and the contacts 2O and 21, which are termed the sending and receiving contacts respectively, are connected to the pole changer armature and the windingV of kreceiving relay-10. An additional leak circuit 24`with a suitable resistance connects the armature of relay 16 tothe armature of relay 1. 'In series with relay 10,. there is also shown a meter' 25. There is also pro-V vided a variable shunt resistance 22 around the winding 17.

vCurrent flowing through the winding 17 tends to hold the armature of the break relay against the sending contact 20. Current through the winding 18 in the leak circuit- 19l opposes the effect of ywinding 1,7 when the armature of the pole changer 1 is on the marking contact, but aids it when the armature is on the spacing contact. By properly proportioning the shunt 22 across the winding 17 and the resistance in the leak circuit 19, the normal line current flowing through the series winding 17 can be made to overpower the effect of the leak winding 18. Under this condition, the armature of the break relay 16 will always stay on the sending contact 20, even though the armature of th'epole changer 1 travels back and forth between its two contacts.

The receiving relay 10 has one winding, one end of which is connected to the 'i'eceiv ing contact 21 ofthe break relay 16,. and the other end to ground. A leak circuit 23' from the spacing battery 2 to thevreceiving contact 21 ofthe break relay serves to hold the armature of the receiving relay 10 to its marking contact, thereby closing the loop circuit when the local subscriber at A is sending. The leak circuit 24 from the marking battery 3 through the armature of the pole changer 1 to the line L neutralizes the effect of the holding leak circuit 23 when the armature of the` break relay is on the receiving contact 21. Accordingly, the only current flowing through the receiving relay 10 under this condition is that from the distant end of the lin-e. If desired, one of the leak circuits 23 or 24 may be made variable, thereby permitting the receiving relay 10 to be biased to counteract ground potentials and biased signals. The meter 25 in .series with the receiving relay will be found helpful in such cases..

The apparatus at station B is substantially the same as that at station A with the exception that oppositely poled batteries from those utilized at station A are provided for sending marking and spacing impulses. In other words, if the battery 8 at station A, utilized for marking impulses, is negative, then the battery 3, utilized at station B for marking impulses, will be positive, and, similarly, if spacing battery 2 at station A is positive, then spacing battery 2 at station B will be negative. The reasons therefor will appear more fully from the following detailed description of the operation of the device.

If the local subscriber at A is sending, the line L will be grounded at the distant station B through the receiving relay. The local receiving relay 10 will then be held on its marking contact under the influence of the holding leak circuit 23, and the pole changer 1 will be operated under the infiuence of the subscribers key K. When the armature of the pole changer 1 rests on its spacing contact, the armature of the break relay 16 will be held against the sending contact 20 under the influence of the current through the winding 18 in the leak circuit 19. lVhen the armature of the pole changer 1 rests on the marking contact, the leak winding 18 will tend to operate the b-reak relay armature to the receiving contact 21,

' but will be prevented from so doing by the line current flowing through the winding 17 to the marking battery 3 and overpowering the effect of the leak winding 18. The local subscriber at A, therefore, can continue to send.

lVhen the local subscriber at A is receiving, the armature of the break rela-y 16 will have been tripped to its receiving contact 21 in a manner to be pointed out hereinafter. dien the armature of relay 16 is on the receiving contact 21, the line current is completely disconnected from the windings 17 and 18. These two windings will then be in series with the marking battery 3. Under these conditions, the effect of the winding 18 will be sufficient to overpower the eect of the winding 17 and will serve to hold the armature against the receiving contact 21. The armature of the transmitting relay 1 will be held on its marking contact under the influence of its loop and holding windings 5 and 6 respectively. The holding current in the receiving relay 10 from the cir cuit 23 will be neutralized by an equal and opposite current over the circuit 24 and armature and mar-king contact of relay 1 to the marking battery 3. Accordingly, the receiving relay 10 will only be affected by the line current from the distant stationB which will flow through said relay to ground, operating said relay.

lff the subscriber at A is sending, and the distant subscriber at B wishes to break the. sending subscriber, he opens his key K. The opening of key K causes the armature of the pole changer relay 1 to move to the spacing contact, and accordingly negative spacing battery 2 will be connected to the line. 1f the loca-l subscriber at A is at that time sending a, `spacing signal his pole changer armature will be on positive battery 2, and nothing will happen except that the line current will be doubled. When the local subscriber at A now closes his key to send a marking impulse, his pole changer armature will move to the marking contact and connect the negative marking battery 3 to the line. lith negative battery thus connected to both ends of the line, the line current will be reduced practically to zero, and practically no current will flow through the winding 17. The negative current, however, will fiow through the leak circuit 19 and the winding 18, and will accordingly trip the armature of the break relay 16 from the sending contact 20 to the receiving contact 21. As soon as this occurs, the distant spacing battery will operate the local receiving relay 10 to the spacing' contact, thereby opening the loop circuit and energizing the holding winding of theA pole changer. The leak winding 18 of the break relay 1G will continue to hold the armature of the break relay against the receiving contact 21 as long as the subscriber at A keeps his key closed to receive signa-ls from the distant station B. This it can do, because, as has been previously pointed out, the line. current is completely disconnected from the pole changer armature and from the winding 17, and the windings 17 and 18 are connected in series with the battery 3. Under these conditions, the winding 18 will overpower the winding 17 and render the latter winding ineffective. The subscriber at B has therefore gaine-d control of the circuit and can send until the subscriber at A opens his key to break.

To illustratel how battery was put on the line by the distant subscriber at B, assume that the, local subscriber at A, after receiving a few signals, now intends to break the distant subscriber. He opens his key K, which deenergizes both the loop vand holding windings'of the pole changerl, there.- by operating the armature of the pole changer 1V to the spacing contact S. The current from the spacing battery flowing through the leak winding 1S of the break relay will operate the armature of that relay tothe sending contact 20, thereby disconnecting the line from the receiving relay 10 and connecting it to the armature of the pole changer 1. The local spacing battery 2 will therefore be connected to the line, and will trip the distant bre-ak relay 16 in the same manner as already described with respect to relay 16.

Because of the fact that both the holding winding 6 and the loop winding 5 are de.- energized by the opening of the subscribers key K, the sending subscriber might not receive a clear break signal. His break relay will be operated to the sending contact 2O when he opens his key, and to the receiving Contact when he' closes his key, as long as the breaking subscriber maintains spacing battery on the line. This might produce short clicks in the sending subscriber-s loop circuit, which would be very confusing and prevent satisfactory operation of the system. To avoid this, a lag is introduced in the operation of the holding winding 6 of the pole changer, so that this winding fails to release, in the interval between markings and spacings of ordinary sending. This is accomplished by connecting the spark killer device, consisting of the resistances 13 and 14: and the fairly large condenser 15, across the holding winding circuit. The operation of the holding winding is then as follows:

Assume that the local break relay 16 has just been tripped by the distant spacing battery as the local subscriber at A closes his key to send a marking impulse. The receiving relay will open up, connecting the holding winding in series with the loop. The spark killer will then be charged to a high potential, due to the effect of the loop batteries 11 and 12. The holding circuit, it is pointed out, has such a large resistance compared to the loop that practically the full voltage of the batteries is impressed across it. If one of the loop batteries is then disconnected v.by the opening of the subscribers key, the spark killer will discharge through the holding winding and keep it energized during the period in which the subscriber keeps his key open. The pole changer will therefore fail to release, and a clean break will result.

There is no possibility of the system locking up so as to be inoperative, even if both breakv relays at each station shouldpbe tripped to their respective receiving contacts. vBy an accidental opening of the line, or similar cause, either subscriber can regain control of the line by opening 'his key for along enoughl period to allow the holding,

`windingto become deenergized.

and circuit connection for said break relays whereby the operation of a break relay will depend upon a reduction in the line current due to the connection to the line at eachv sta-k tion of batteries of like polarity.

2. In a telegraph system, a transmission line, a terminal station for said line, said terminal station comprising a pole changer relay Vhaving an armature cooperating with contacts connected to marking and spacing batteries, a receiving relay, and a break relayhaving an armature connected to the line and cooperating with a receiving contact and a sending contact, said receiving contact being connected to said receiving relay and said sending contact being connected to said pole changer armature, said break relay being arranged so as to normally hold its armature against said sending contact whenever the transmission line is grounded at a distant station.

3. In a telegraph system, a transmission line, a terminal station for said line, said terminal station including a receiving relay, a pole changer device, a break relay, the armature of said break relay being connected to said line and being adapted to conneet said line to said receiving relay or to said pole changer device, and circuit arrangements for said break relay whereby the line will be connected through said armature to said pole changer device under all conditions except when the line current is reduced below normal.

4. In a telegraph system, a transmission line, a terminal station for said line, said.

being connected in Series with said line and said pole changer device and the other of said windings being Connected in a leak oilcuit between said line and ground, said sec 5 ond Winding being adapted to overcome the effect of said first Winding only when said windings are directly connected in series,

and the eifeot of said second Winding under said last mentioned conditions being to oonneot said line to said receiving relay.

In testimony whereof, I have signed my name to this specification this 3rd day of Api-i1, 1922.

' JOSEPH HERMAN. 

